Note: PLEASE reply to this topic once you have read it. I really appreciate feedback from people on what could be done better, and will use your comments to improve/extend the tutorial.

This is a tutorial about pixel art.
During this guide, I would like to introduce to aspiring pixel artists on these forums several extremely useful pixel techniques that will help them along their way to becoming great pixel artists. Some of these are very basic, but others need a lot of practice to master. Read this guide, and you will probably learn something useful.

Many tutorials seem to just go on and on and on, and get quite tiresome to read after a while. However, I'm trying to keep my guide as short and concise as possible, while making sure everything makes perfect sense. You may use this as a short reference to all the pixel techniques you know. If you know any that you'd like me to write about, please post in this topic! (I'm sure that if you just mention the term, I will recognize it).

What Am I Teaching You in this Tutorial?
- How to work with clean lines.
- How to create clean lines and circles.
- What dithering is, and in what cases to use it.
- How to shade correctly, and what not to do when shading.
- How to place the shadows of objects.
- How to smooth out your lines to not look as 'pixelly'.

Clean Lines

Not really a technique, but is a must-do for all pixel artists. Keep your lines clean by keeping it one pixel wide all along... my image pretty much explains itself.

One thing: don't start your lineart with clean lines directly. You'll get things done much better if you make a rough sketch of what you want (as messy as you want), then clean the lines afterwards.

Straight Lines and Perfect Circles

Straight Lines

You've all heard of the Line Tool? You've probably also used it. Don't use the line tool for pixel art again, unless for straight lines (Hold 'Shift' while creating a line to make it perfectly straight! Works in most programs). Why, you ask? Because the result will be a very jagged, unclean (yes, when I mean unclean, I mean the same uncleaniness as in the previous section) line! Instead of using the line tool, make your lines suited for pixel art (a regular line that is clean and not jagged). Here follows a little sample of commonly use line angles. The fractions represent the slope or gradient of the line. ex: 2 / 1. 2 = advancement in the 'y' axis (pixels that go up) and 1 = advancement in the 'x' axis (pixels that go right).

There are of course more line slopes, such as 3 / 1 or 1 / 4, but my point is that if you keep your lines regular and following a good pattern, your work will look neater than never before.

Perfect Circles

Yes, I am going to say the exact same thing about circles that I said for lines. This time, my reason is that pixel art is a low resolution art. So low that the mathematical formulas in programs like MS Paint or Photoshop give us a rough approximation of the shape we wanted originally, and the result is a dirty-looking, rough circle. In pixel art, it is relatively easy to make perfect circles, but it takes practice to get it right the first time. Here are the steps to making them:

1. Depending on how large you make your circle, the pattern of how you place your pixels changes. For example, for this medium-sized circle I used 2,2,1,1,2,2. Once you've finished this quarter, copy it, paste it, flip it around and paste the second quarter under the first.

2. You know have a semi-circle, with a pattern of 2,2,1,1,2,4,2,1,1,2,2 pixels. Notice how the sides have the most aligned pixels and the bends have the least number of pixels in a row in them.

3. Copy the semi-circle, paste it and flip it and you now have your circle!

4. Some sample circles I've made, to show you how to make them in different sizes.

You've probably noticed that choosing the correct pattern for your circles is the hardest part in making these. It took me a couple of rugby balls to get a perfect sphere when I first practiced these. Once you make a few however, you'll get the hang of it, and your circles will start becoming perfect circles and not rugby balls.

Dithering

The most basic technique of pixel art, and probably the first you should learn. It consists of using patterns of two colors in order to create the illusion that there are more colors. Can also be used to create texture.
Note: do not overuse! A lot of beginner pixelers tend to become religious to dithering. Dithering is by no means necessary.

This is a small blown-up demonstration of some good dithering patterns (400% of actual size). Notice that I only used two colors (the purple at the left and the orange at the right), but created the illusion that there were many more colors. Why is this useful, do you ask? Firstly, because it saves a lot of useless color-choosing. The fewer the colors, the more time you're spending doing the actual sig. It is also, in some cases, a great way to give texture to an object such as a tree's rough bark, or some ragged clothing.

What I suggest you don't do, is to dither on highly reflective surfaces (such as a window or polished metal). Reflective surfaces are that way because they're extremely smooth and hard, and it wouldn't look good to give them too much rough texture.

Shading

This is where a lot of newbs mess up. There is only one way of shading, and that's the correct way. One of the most common wrong ways of shading is pillow-shading. Pillow shading is taking the object you're trying to shade, and make the edges of that object dark, then progressively working your way into lighter and lighter tones until you reach the middle.
The result is a somewhat grotesque interpretation that looks like a fluffy pillow... where pillow-shading takes its' name from. What follows is a demonstration of what pillow-shading is, and what correct shading is.

Tell me... which of those two spheres looks the most genuine. Which looks more real? You probably chose the bottom one, and for reason: it has a light source. The arrow shows where the light is hitting the sphere, and that's where its colors are the lightest. The pillow-shaded one doesn't look real because it doesn't really have a light source. The only possible light source would be between the viewer and the sphere (in the center), which is impossible since we can't see it.
Besides, if we ignore that, choosing your light source to be in the center is a horrible design choice, and other objects in the scene would have to be shaded according to that same light-source. (ex: with the light source in the center, a sphere positioned to our left of the light source have have more shadow on the left side than the right side)

Now that I have (hopefully) persuaded you never to pillow-shade again (or ever, if you haven't pillow-shaded yet), I will teach you how to shade the correct way. I can only teach you this much, as shading is a skill that requires a lot of practice to perfect. However, I can help you on your path.

The secret of shading correctly sounds pretty simple, but actually isn't at all. Once you have a rough sketch of what you want your sig scene to look like, the first thing you should do is choose a light source. A light source is where the light is going to be coming from. Once you have done that (let's say your light source will be a late afternoon sun, somewhere in the top right of your sig), you can determine which surfaces will be hit by the light and which surfaces will be in shadow (a pillar's left side will be darker than the right side in this case).

Determining Shadow Contours

For simple objects such as this one, one can easily determine where it will cast its' shadow on the ground. As illustrated on the image, drag a line from one extremety of the light source through the of the same side of the object. Repeat with the other extremety and you have a perfect cast shadow.

Anti-Aliasing

We've already gone through my "clean lines" section, and now we are moving into one of the more advanced techniques of pixel art. Maybe you've heard of anti-aliasing before, maybe you haven't. In both cases, I'm going to explain it to you.

You've probably done some black lineart on a white background before, right? Did you notice how jagged and 'pixelly' the lines were? That's because of the high contrast between the black and white. Anti-aliasing can help you throw away all those jaggy lines, and make brand new, smooooth lines. Demo:

Notice how the version on the left is so much smoother than the one on the right? Anti-aliasing uses the method of an average of two colors (in this case, (black + white) / 2 = gray!) to smooth out the contrast difference. I didn't only use one color to smooth this out though, because black and white are the highest possible color contrasts, so I needed to average the first average of black and white again to make this line look as smooth as possible.

Phew, all this stuff is hard to explain. I hope I was clear and concise enough during this guide, and that you learnt something useful whilst reading it. I will probably extend it when I have enough time.

edit@rangedwild: I reformulated the sentence, I hope it is clearer now. As for the dithering pattern, I can't come up with a better one for this situation.. I have learned many dithering patterns and think the one I used is the best one to use (in this case).

I used to pixel (not very well, I should add), back in the day, until I finally gave it up. I sure wish I would have read this tutorial when I was still pixeling, I think I would have been much better off. Also, from what I saw, you have pretty much all the basics. Maybe do some small, simple tutorials on how to draw hands, faces, or feet? From what I've seen, that's what people seem to have the most trouble with. If you did a couple tutorials on those, it could be pretty useful.

Nice work!

"I shall take the heart... for brains do not make one happy, and happiness is the best thing in the world." - The Tinman